A steering column generally includes a main column, a tilt head, and a pivot joint, such as a universal joint, which pivotably connects the tilt head to the main column. A steering wheel is mounted on the tilt head. The pivot joint rotatably fixes the tilt head to the main column to allow the rotation of the steering wheel to be transmitted from the tilt head to the main column. However, the pivot joint allows the tilt head to pivot relative to the main column so that the driver can adjust the tilt angle in accordance with his preference.
The steering column also includes a tilt setting device which the driver can use to adjust the tilt angle of the tilt head and to set the tilt head at a desired tilt angle. The tilt setting device may have an elongated configuration with two ends. One end of the tilt setting device is connected to the main column, and the other end is connected to the tilt head. The length of the tilt setting device may be adjusted to adjust the tilt angle of the tilt head.
The tilt setting device may include a sleeve and a rod which is disposed telescopically in the hollow center of the sleeve. Each of the sleeve and rod has first and second ends. The second end of the rod extends into the hollow center of the sleeve from the first end side of the sleeve. The first end of the rod is preferably coupled pivotably to one of the main column and tilt head, and the second end of the sleeve is preferably coupled pivotably to the other of the main column and tilt head. Preferably, the rod is pivotably coupled to the one of the main column or tilt head with a pin that extends through a hole on the rod. Similarly, the sleeve may be pivotably coupled to the other of the main column or tilt head with a pin that extends through a hole on the sleeve. The pins may be fixed to the respective main column and tilt head. The length of the tilt setting device may be defined as the distance between the first end of the rod and the second end of the sleeve.
The length of the tilt setting device may be adjusted by sliding the rod relative to the sleeve telescopically, i.e., in the longitudinal direction. The length of the tilt setting device may be set by securing the rod to the sleeve in the longitudinal direction to prevent relative longitudinal movement between the sleeve and the rod.
To secure the rod to the sleeve, the hollow center of the sleeve may have an inner surface that has length-wise opposite surfaces and width-wise opposite surfaces, wherein the length-wise surfaces may be spaced farther apart than the width-wise surfaces. Preferably, the width-wise opposite surfaces are threaded, and the length-wise opposite surfaces are unthreaded. Additionally, the outer surface of the rod may also have length-wise opposite surfaces and width-wise opposite surfaces, wherein the length-wise opposite surfaces are threaded, and the width-wise opposite surfaces are unthreaded.
Preferably, the hollow center of the sleeve and the rod are dimensioned so that when the threaded width-wise surfaces of the sleeve's hollow center face the threaded length-wise surfaces of the rod, the inner threads of the hollow center engage the outer threads of the rod to prevent the rod from sliding relative to the sleeve telescopically. On the other hand, when the threaded width-wise surfaces of the sleeve's hollow center face the unthreaded width-wise surfaces of the rod, the inner threads of the hollow center disengage the outer threads of the rod to allow the rod to slide relative to the sleeve telescopically.
With this arrangement, the locking and unlocking of the rod with the sleeve can be accomplished by rotating the sleeve relative to the rod or by rotating the rod relative to the sleeve. When the rod and sleeve are pivotably coupled to the respective main column and tilt head, in order for the rod or sleeve to rotate, the hole on the rod or sleeve, through which the pin extends to pivotably couple the rod or sleeve to the respective main column or tilt head, may have an elongated configuration and may extend laterally, i.e. may extend in a direction perpendicular to the longitudinal direction of the rod and sleeve. As the rod or sleeve rotates, the pin slides in the laterally extending, elongated hole.
Normally, the rod is locked with the sleeve to set the tilt head at a desired angle, and the pin is located at a first end of the elongated hole. In order to unlock the rod with the sleeve to adjust the tilt angle, the rod or sleeve is rotated, and the pin moves from the first end of the elongated hole to the second end. In order to facilitate the movement of the pin from the first end of the elongated hole to the second end, the elongated hole may be tapered with the second end wider than the first end, i.e. at least one side of the elongated hole is tapered.
The tilt setting device may include a spring that biases the rod or sleeve towards the locked position with the pin located at the narrower end of the elongated hole. To reset the tilt angle, the rod or sleeve is rotated to the unlocked position against the spring torque with the pin moving from the narrower end of the elongated hole to the wider end. After the tilt angle has been reset, the rod or sleeve is released to allow it to return to the locked position under the spring torque.
Applicant has recognized a problem associated with prior art tilt setting devices. The problem is that, when any force is applied to the tilt setting device in the longitudinal direction, the tapered side(s) of the elongated hole tends to push the pin towards the wider end of the elongated hole and to rotate the rod and sleeve in the unlocked direction. This may accidentally unlock the tilt setting device when the rod and sleeve are in the unlocked position.
In the present invention, to prevent this from happening, at least one of the sides of the elongated hole may be untapered near the narrower end of the elongated hole. The untapered region may be generally defined as a region that does not have an increased width in the direction of the wider end of the elongated hole. Preferably, the untapered region is a flat region. When the pin is at the narrower end of the elongated hole, the pin is in, or rests against, the untapered region. Consequently, when the rod or sleeve is at the locked position (i.e. when the pin is at the narrower end of the elongated hole), longitudinal forces applied to the tilt setting device can no longer cause the pin to move towards the wider end of the elongated hole and cause the rod and sleeve to rotate in the unlocked direction.
As defined herein, the words “length-wise” and “width-wise” do not imply that the cross sections of the rod and sleeve's hollow center have a rectangular configuration or even an oblong configuration. In certain cases, they simply mean that the rod or sleeve's hollow center has two opposite surfaces (length-wise surfaces) that are farther apart that two other opposite surfaces (width-wise surfaces). For example, the sleeve and rod may each have an elliptical cross-section. The length-wise opposite surfaces may be the surfaces at the opposite ends of the major axis of the ellipse, and the width-wise opposite surfaces may be the surfaces at the opposite ends of the minor axis.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.